Related Experiment Videos
Class II MHC antigen-positive macrophages from human placentae suppress strong MLR and CML reactions
1Department of Microbiology, University of Melbourne, Parkville, Victoria, Australia.
Abstract:
Placental adherent cells (PAC), derived by mild enzymic digestion of human placentae and adherence to plastic, were tested for their ability to suppress MLR and CML reactions. Stimulation of allogeneic T cells by cord blood mononuclear cells or by a strongly stimulatory B lymphoblastoid cell line were consistently inhibited by all PAC preparations tested. PAC were fractionated by Fc rosetting and Percoll gradients to produce a number of bands. Suppression correlated with the content of macrophages in each band and was strongest in band 5 which generally contained 94-100% macrophages. The suppressive effect was not inhibited by indomethacin. The possible role of macrophages in suppressing immune reactivity in the placenta is discussed.
Insights
Placental adherent cells (PAC) suppress immune responses by inhibiting T cell stimulation. Macrophages within PAC, particularly in band 5, are key to this immune suppression in the placenta.
Area of Science:
- Immunology
- Cell Biology
- Reproductive Biology
Background:
- Placental adherent cells (PAC) are isolated from human placentae.
- The immune functions of PAC, particularly their suppressive capabilities, are not fully understood.
Purpose of the Study:
- To investigate the immune suppressive properties of PAC.
- To identify the specific cell types within PAC responsible for immune suppression.
Main Methods:
- PAC were isolated from human placentae via enzymic digestion and adherence to plastic.
- Suppressive effects on mixed lymphocyte reaction (MLR) and cytotoxic MLR (CML) were assessed.
- PAC were fractionated using Fc rosetting and Percoll gradients.
- Macrophage content in fractions was quantified.
Main Results:
- All tested PAC preparations inhibited allogeneic T cell stimulation.
- Immune suppression correlated with macrophage content, with band 5 (94-100% macrophages) showing the strongest effect.
- Indomethacin did not inhibit the suppressive effect.
Conclusions:
- PAC possess significant immune suppressive capabilities.
- Macrophages are the primary mediators of immune suppression by PAC.
- These findings suggest a role for macrophages in regulating placental immune tolerance.